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LAB ____. ANATOMICAL EVIDENCE OF EVOLUTION In our studies of the anatomy and development of animals we have discovered that many living creatures that look quite different on the surface have similarities underneath their skin that suggest that they are related to each other. This is evidence that living creatures have evolved, or gradually changed over time. In this lab, you will learn about homologous, analogous, and vestigial structures and their value as evidence for evolution.
INSTRUCTIONS A. HOMOLOGOUS STRUCTURES
There are many examples of body structures that are formed in similar ways during embryonic development and that share similar patterns of bone structure, even though they take on different forms and perform somewhat different functions. These structures are called homologous structures. Homo- means same, and -logous means information, so homologous means “same information”. Homologous structures mean that the animals share a relatively recent common ancestor. 1. Carefully examine the drawings of forelimb skeletons shown in Figure 1 on the next page. Look for similarities in the bones amongst the various animals. 2. Color in the human arm first. Color the bones of the arm (the humerus, ulna, and radius) blue. Color the bones of the hand (the carpal, metacarpals, and phalanges) yellow. 3. Color the corresponding bones in each of the other animals the same color as the human bones. 4. Observe each of the skeletons again, and describe the function of each limb in the table below: Animal human whale cat bat bird crocodile 5. Answer the Summary Questions. Function
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Name _____________________________ Figure 1.
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B. ANALOGOUS STRUCTURES